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The Colorado River
The Colorado River is the primary river of the American Southwest, draining somewhere in the vicinity of 242,000 square miles of land, from the states of Wyoming, Colorado, Utah, New Mexico, Arizona, Nevada and California. The Green River is the primary tributary of the Colorado River, and until 1921 the Colorado River did not technically begin until the Grand and Green Rivers joined together in Utah. In that year the Grand River was renamed as the Colorado River, at the request of the State of Colorado . The river contains alternating sections of rapids and calm sections. The depth of the river varies from 6 feet to 90 feet, with the average being about 20 feet. The rapids are the shallow sections and the calm sections tend to be the deepest parts. Some deep holes have also formed at the base or foot of some of the more major rapids. The rapids represent only 10 percent of the river's total length through the Grand Canyon, but are responsible for more than half of the total drop in altitude. The Colorado River was originally named Rio Colorado or "Red River" by the Spanish. A person looking at the river today may not understand how it came to be named in this way, as the present day color of the river is more of a blue-green. The reddish-brown color that originally gave the river its name become a rarity upon completion of the Glen Canyon Dam in 1963. The silt and sediments that gave the river its color are now trapped behind the dam in the bottom of Lake Powell. The primary purpose for construction of the Glen Canyon Dam was to prevent silt from building up behind another dam,Hoover Dam on the other side of the Grand Canyon, at the head of Lake Mead http://www.holydieexplorer.com/grand-canyon-dams-on-the-colorado-river-in-arizona-usa/ The Hoover Dam At the time of construction (1935), Hoover Dam was the largest in the world and although long since surpassed it is still an amazing structure and a marvel of engineering - a huge, curving wall of plain concrete 660 feet thick at the base and 726 feet high set between the vertical walls of''' Black Canyon', accompanied by strangely-angled pylons, cables, power generating plants and other machinery. In 1955, the dam was selected as one of the Seven Modern Engineering Wonders in the USA by the American Society of Civil Engineers, and it is was later designated a National Historic Landmark. Also known as Boulder Dam, the usual name commemorates the 31st president Herbert Hoover, who was in office during the start of the project. 'thumb|300px|left' 'Irrigating the southwest' More than 1,000 years ago, Native Americans irrigated their crops with the waters from the river. And today that is still the case. It is said that the Colorado River is the "lifeblood of the southwest" since it provides the essential irrigation and domestic water needed for the entire southwest through various canals. Without this water the entire agriculture in the imperial valley would disappear since that region only counts with less than 3 inches of annual rainfall. '"The law of the river"''' The Colorado River is managed and operated under numerous compacts, federal laws, court decisions and decrees, contracts, and regulatory guidelines collectively known as the "Law of the River." *The Colorado River Compact of 1922 *The Boulder Canyon Project Act of 1928 *California Seven Party Agreement of 1931 *The Mexican Water Treaty of 1944 *Upper Colorado River Basin Compact of 1948 *Colorado River Storage Project of 1956 *The Arizona v. California U.S. Supreme Court Decision of 1964 *The Colorado River Basin Project Act of 1968 *The Criteria for Coordinated Long-Range Operation of Colorado River Reservoirs of 1970 (amended March 21, 2005) *Minute 242 of the U.S.-Mexico International Boundary and Water Commission of 1973 *The Colorado River Basin Salinity Control Act of 1974 http://www.usbr.gov/lc/region/g1000/lawofrvr.html